In a Long Term Evolution (LTE)/Long Term Evolution Advanced (LTE-A) communications system, a downlink multiple access mode is usually an orthogonal frequency division multiple access (OFDMA) mode. A main feature of the orthogonal frequency division multiple access mode is that different user equipments (UEs) use different time-frequency resources to ensure no interference to received signals of the different UEs, and implement simple reception on a UE side. However, when communication is performed in the orthogonal frequency division multiple access mode, utilization of time-frequency resources is relatively low, resulting in limitation on an overall transmission rate of a communications system.
In a non-orthogonal multiple access (NOMA) transmission mode, information of multiple UEs can be transmitted on a single resource element (RE). Compared with OFDMA, NOMA improves an overall transmission rate of a system. Further, in a semi-orthogonal multiple access (SOMA) transmission mode, a property of Gray code in an existing modulation scheme (or constellation diagram) is used, so that a receiver of UE may use a simple receive algorithm, to further improve system performance.
However, in an SOMA communication process of an LTE system, a downlink control parameter transmission method adapted to SOMA communication is required.